On the Nephridia of Perichaeta. 



309 



January 12, 1888. 



Professor G. G. STOKES, D.C.L., President, in the Chair. 



The Right Hon. Arthur James Balfour, whose certificate had been 

 suspended as required by the Statutes, was balloted for and elected a 

 Fellow of the Society. 



The Presents received were laid on the table and thanks ordered for 

 them. 



The following Papers were read : — 



I. " Preliminary Note on the Nephridia of Perichaeta.'" By 

 Frank E. Beddard, M.A., Prosector to the Zoological 

 Society of London, Lecturer on Biology at Gny's Hospital. 

 Communicated by Professor E. Ray Lankester, M.A., 

 LL.D., F.R.S. Received December 21, 1887. 



The following observations are the result of a study of a species of 

 Perichaeta, which is probably identical with Perrier's P. asperg ilium.* 

 I owe a number of excellently preserved examples to the kindness of 

 Mr. Shipley, Fellow of Christ's College, Cambridge. 



In transverse sections of the anterior segments the nephridia are 

 seen to form numerous tufts of glandular tubules closely related to 

 the body-wall and to the septa. This appearance, which is also seen 

 in dissections, is very different from that of most other earthworms, 

 and has been commented upon by other observers. Perrier, in fact, 

 expressed the opinion that these organs in Perichaeta are in a rudi- 

 mentary condition. I shall, however, bring forward reasons for 

 believing that they are in a very archaic condition. 



The remarkable appearance of the nephridia led me to infer that 

 I should find the external apertures in each segment to be numerous, 

 as I showed to be the case in Acanthodrilus.f I may take the oppor- 

 tunity of stating that in the latter species (A. multiporus) there is 

 apparently a very much greater number of nephridiopores in the 

 anterior than in the posterior segments ; in certain of the anterior 

 segments I counted over one hundred. I am now able to state that 

 this is also the case in Perichaeta (in all probability in other species 

 besides P. asperg ilium). The external pores lie between the seta?, 

 but have no regularity in their arrangement ; frequently there were 

 three or four between two successive setce, as often there seemed to 



* 'Paris, Mus. Hist. Nat. Nouv. Archives,' 1872. 

 f ' Roy. Soc. Proc.,' 1885. 

 VOL. XLIII. 2 A 



